Fair Value and Gross Unrealized Losses on Available-for-Sale Securities (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value	$ 2,304		$ 7,849
Less than 12 months Unrealized Losses	(19)		(157)
12 months or more Fair Value	213		137
12 months or more Unrealized Losses	(4)		(2)
Total Fair Value	2,517		7,986
Total Unrealized Losses	(23)		(159)
Agency mortgage-backed securities | Residential mortgage backed securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value	573		7,221
Less than 12 months Unrealized Losses	(6)		(150)
12 months or more Fair Value	107		1
12 months or more Unrealized Losses	(2)
Total Fair Value	680		7,222
Total Unrealized Losses	(8)	[1]	(150)	[1]
Agency mortgage-backed securities | Commercial mortgage backed securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value	1,509
Less than 12 months Unrealized Losses	(11)
Total Fair Value	1,509
Total Unrealized Losses	(11)
Non-agency mortgage-backed securities | Commercial mortgage backed securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value			168
Less than 12 months Unrealized Losses			(1)
12 months or more Fair Value			28
Total Fair Value			196
Total Unrealized Losses			(1)
Asset-backed securities and other debt securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value	215		427
Less than 12 months Unrealized Losses	(2)		(5)
12 months or more Fair Value	76		104
12 months or more Unrealized Losses	(1)		(2)
Total Fair Value	291		531
Total Unrealized Losses	(3)		(7)
Equity securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value	7		33
Less than 12 months Unrealized Losses			(1)
12 months or more Fair Value	30		4
12 months or more Unrealized Losses	(1)
Total Fair Value	37		37
Total Unrealized Losses	$ (1)	[2]	$ (1)	[2]

[1] Includes interest-only mortgage-backed securities of $192 and $262 as of September 30, 2014 and December 31, 2013, respectively, recorded at fair value with fair value changes recorded in securities gains, net and securities gains, net non-qualifying hedges on mortgage servicing rights in the Condensed Consolidated Statements of Income.

[2] Equity securities consist of FHLB and FRB restricted stock holdings of $249 and $351, respectively, at September 30, 2014 and $402 and $349, respectively, at December 31, 2013, that are carried at cost, and certain mutual fund and equity security holdings.